Problem: Rearrange the equation so $w$ is the independent variable. $-2u+6w=9$ $u=$
To arrive at a correct equation, we have to solve the equation for $u$. $\begin{aligned}-2u+6w&=9\\\\ -2u&=9-6w\\\\ u&=\dfrac{9}{-2}-\dfrac{6w}{-2}\\\\ u&=-\dfrac{9}{2}+3w\end{aligned}$ The following equation is rearranged so $w$ is the independent variable: $u=-\dfrac{9}{2}+3w$